Korea emerged as a singular political entity after centuries of conflict among the Three Kingdoms of Korea, which were unified as Silla (57 BC – AD 935) and Balhae (AD 698 – 926). The united Silla was eventually succeeded by Goryeo in 935 at the end of the Later Three Kingdoms period. Goryeo, which gave name to the modern exonym "Korea", was a highly cultured state and created the Jikji in the 14th century. The invasions by the Mongol Empire in the 13th century, however, greatly weakened the nation, which forced it into vassalage. After the Yuan dynasty's collapse, severe political strife followed. Goryeo eventually fell to an uprising led by General Yi Seong-gye, who established Joseon in 1388.